Japanese Patent Application Laid-Open No. 2011-193678 describes a direct power converter. The direct power converter includes a diode rectifier, an inverter, and a charge-discharge circuit. The diode rectifier full-wave rectifies a single-phase AC voltage and outputs the resultant voltage to a DC link. The diode rectifier full-wave rectifies the single-phase AC voltage and outputs the resultant voltage to a pair of DC power lines (DC link). The charge-discharge circuit is provided in the DC link and includes a buffer circuit and a booster circuit. The buffer circuit has a switch and a capacitor connected in series between the pair of the DC power lines. The switch is located on a positive side of the DC link relative to the capacitor. Making the switch conducting discharges the capacitor to feed power to the DC link. The booster circuit raises the rectified voltage from the diode rectifier to charge the capacitor. In this way, the charge-discharge circuit receives the power from the DC link. The DC voltage is input from the DC link to the inverter. The inverter converts the input DC voltage to an AC voltage and outputs the resultant voltage.
Japanese Patent No. 4135026, Japanese Patent No. 4718041, Japanese Patent No. 3070598, “Capacitance Reduction and Basic Investigation method of A Novel Single-Phase to Three-Phase Power Converter,” written by Yoshiya OHNUMA and Jun-ichi ITOH, Papers of Technical Meeting on Semiconductor Power Converter, IEE-Japan, SPC-08-162 (2008), “Circuit Configuration and Control Strategy of Single-Phase to Three-Phase Power Converter using Active Buffer with Charge Circuit,” written by Yoshiya OHNUMA and Jun-ichi ITOH, IEE-Japan 2010 National Convention, 4-057 (2010) and “Experimental Verification of Single-Phase to Three-Phase Power Converter Using Active Buffer with Charge Circuit,” written by Yoshiya OHNUMA and Jun-ichi ITOH, IEE-Japan 2010 Industry Applications Society Conference, 1-124 (2010) disclose techniques relating to the present disclosure.